Start by downloading and installing ewtoo on your own machine, from ewtoo.org.Then pick something you want to modify, and work out how. (Feel free to ask again when you get this far.)EWToo is in C, so you should get a good book on programming in C.

Learn coding? I guess you mean you know nothing about programming?I'd start learning C some other way :)

You could just download pgplus or some other code base and compile it on your friend's handy linux box following the readme instructions and then pull apart the code with any old text editor changing things around like the text messages until your feel happy modifying it and understand how to fix the silly syntax errors you will make....